Because CD has the characters of high density, and completely digital recording, it has become the main digital data recording medium, and has been widely applied in optical disk players, such as CD, CD-ROM, VCD, DVD, LD and MD, more and more involved in people's daily life. In the existing compact disc players, there are mainly two types of transmission mechanisms used in CD driving systems that load and unload CDs, the first type is loading CDs into or unloading CDs from the disk players through a disk tray, a driven rack is employed underneath the disk tray, when the contact switch is turned on, a motor drives a driving gear to rotate, the driving gear then drives the disk tray in and out of the disk player by driving the driven rack operation, the structure of this type of transmission mechanism for the disk driving system is more simple in terms of its structure, but because the disk tray is required, and after loading the disk into the disk player, a gap needs to be preserved between the CD and the disk tray to ensure the CD driven by the motor is turning smoothly, the thickness of the disk driving system is then substantial, which is not satisfactory to consumers' demand of super thin and appealing appearances; particularly, because the CD tray can only go straight in and out of the disk player, in order to raise the CD to keep a certain gap between the CD and the disk tray, it is necessary to design the connections between those members like a spindle motor that drives the CD to rotate, a laser head, a collimating lens etc. of the optical pickup mechanism and other fixtures to be flexible; hence, it is difficult to make sure those members like a laser head, a collimating lens etc., are placed into an accurate corresponding position of the inserted CD and therefore very difficult to avoid vibration, which directly affects the correctness of data reading, especially after a long term usage, this problem becomes even more obvious when some members are worn out; another type of transmission mechanism used in disk player driving system is the receiving, ejection type, mainly used in vehicle disk players, including position switches, when users insert a CD into the slot, the CD triggers the position switch inside the disk player, and activates the motor, the driving gear starts to rotate, through the transmission of the driven rack, the friction created by the contact between the driving gear and the CD brings the CD into the disk player, and places the CD in the position corresponding to the position of the spindle motor, the driving gear is then moving downward under the operation of the motor, and a gap is created between the CD and the driving gear, after been clamped by the clamping means, the CD driven by the spindle motor starts to rotate, and the related members start reading data, etc., the structure of this type of transmission mechanism of disk driving systems, the CD optical pickup mechanism can be fixed, a normal data reading can be guaranteed, and the thickness is much smaller; however, the transmission mechanism is complicated, requiring higher manufacturing accuracy, higher cost.